Preface ........................................................ xv
l. Silicon Nanoparticles: New Photonic and
Electronic Material at the Transition
Between Solid and Molecule ................................... 1
Munir H.Nayfeh and Lubos Mitas
1.1. Introduction ............................................... 3
3.1.2. Synthesis ........................................... 3
1.2.1. Physical Techniques ................................. 3
1.2.2. Physico-Chemical Techniques ......................... 4
1.2.3. Chemical Techniques ................................. 4
1.2.4. Electrochemical Techniques .......................... 4
1.2.5. Discretely Sized Si Nanoparticles ................... 6
1.3. Functionalization .......................................... 8
1.3.1. Initial Surface Condition ........................... 9
1.3.2. Alkylated Particles ................................ 11
1.3.2.1. Alcohol ................................... 11
1.3.2.2. Alkylamine ................................ 13
1.3.2.3. Alkene .................................... 14
1.3.2.4. Carboxy ................................... 14
1.3.2.5. Alkyl and Alkoxy .......................... 15
i.3.З. Aggregation and Solubility ......................... 15
1.3.4. Stability in Acid .................................. 17
1.4. Spectroscopic Characterization ............................ 17
1.4.1. Fourier Transform Infrared Spectroscopy ............ 17
1.4.2. Nuclear Magnetic Resonance ......................... 19
1.4.3. Gel Permission Chromotography ...................... 20
1.4.4. X-Ray Photospectroscopy ............................ 21
1.4.5. Auger Electron Spectroscopy ........................ 21
1.4.6. Transmission Electron Microscopy ................... 21
1.5. Optical Properties ........................................ 22
1.5.1. PL and Detection of Single Nanoparticles ........... 22
1.5.2. PL Lifetime ........................................ 26
1.5.3. Cathodoluminescence and Electroluminescence ........ 27
1.5.4. Photostability Under UV and Infrared Radiation ..... 29
1.6. Reconstitution of Particles in Films ...................... 29
1.6.1. Precipitation Spray ................................ 30
1.6.2. Electrodeposition: Composite Films of Metal and
Nanoparticles ...................................... 31
1.6.3. Silicon Sheet Roll into Tubes ...................... 32
1.6.4. Self-Assembly ...................................... 33
1.7. Nonlinear Optical Properties .............................. 34
1.7.1. Stimulated Emission ................................ 34
1.7.2. Second Harmonic Generation ......................... 39
1.7.3. Gain and Optical Nonlinearity ...................... 39
1.8. Effect of Functionalization on Emission ................... 41
1.9. Structure of Particles .................................... 41
1.9.1. Luminescence Models ................................ 42
1.9.2. Computational Methods for Electronic Structure
of Nanoclusters .................................... 43
1.9.2.1. DFT Methods ............................... 44
1.9.2.2. Quantum Monte Carlo ....................... 45
1.9.2.3. Variational Monte Carlo ................... 45
1.9.2.4. Diffusion Monte Carlo ..................... 46
1.9.2.5. Applications to Si Clusters ............... 46
1.9.3. Prototype of Hydrogenated Particles
(Supermolecule) .................................... 49
1.9.4. H2O2 Effect on Surface Reconstruction .............. 51
1.9.5. Novel Si-Si Bonds (Molecular-Like Behaviour) ....... 52
1.9.6. Structural Stability of the Prototype .............. 54
1.9.7. Material Properties: Dielectric Constant and
Effective Mass ..................................... 55
1.9.8. Excited States (Molecular-Like Bands) .............. 57
1.9.9. Collective Molecular Surface ....................... 57
1.9.10.Phonon Structure: Collective Molecular Vibration
Modes .............................................. 59
1.9.11.Molecular-Like Emission: Direct versus Indirect
Process ............................................ 60
1.9.12.X-Ray Form Factors ................................. 61
1.9.13.Effect of Termination on the Band Gap .............. 63
1.10.Device Applications ....................................... 63
1.10.1.Photoelectric Conversion/UVPhotodetector ........... 64
1.10.2.Metal Oxide Silicon Memory Devices ................. 66
1.10.3.Biophotonic Imaging ................................ 68
1.10.4.Amperometric Detection ............................. 69
1.10.5.Nanosolar Cell ..................................... 71
1.10.6.Nanoink Printing ................................... 72
1.10.7.Single Electron Transistor Devices ................. 73
1.11.Conclusion ................................................ 73
Acknowledgements ............................................... 74
References ..................................................... 74
2. Cluster Assembled Silicon Networks .......................... 79
P.Melinon, X.Blase, A.San Miguel and A.Perez
2.1. Introduction .............................................. 80
2.2. Isolated Silicon Clusters ................................. 81
2.2.1. Small Siw Clusters (W < 14) ........................ 81
2.2.2. Medium-Sized Clusters (20 < N < 100):
the Case of Si33 ................................... 82
2.2.3. Large Clusters (N > 100) ........................... 82
2.3. Si-Cluster-Assembled Materials ............................ 83
2.3.1. Introduction ....................................... 83
2.3.2. Si-Cluster-Assembled Films ......................... 83
2.3.2.1. Gas-Phase Synthesis of SiN Clusters:
Experimental Methods ...................... 83
2.3.2.2. Structure and Morphology .................. 86
2.3.2.3. Electronic Structure ...................... 90
2.3.2.4. Vibrational Structure ..................... 90
2.3.2.5. Optical Properties ........................ 92
2.3.2.6. New Bonding for Silicon ................... 93
2.3.3. Bulk Si-Cluster-Assembled Materials from
Fullerenes: Clathrate Phases ....................... 97
2.3.3.1. Silicon Clathrate Structures .............. 98
2.3.3.2. Synthesis Methods ........................ 100
2.3.3.3. Electronic Properties of Empty
Silicon Clathrates ....................... 100
2.3.3.4. Vibrational Properties ................... 101
2.3.3.5. Cohesive Energy and Stability Under
Pressure of Si-34 ........................ 103
2.3.3.6. Endohedral Doping in Clathrates .......... 104
2.4. Conclusion ............................................... 110
Acknowledgements .............................................. 110
References .................................................... 111
3. Metal Encapsulated Clusters of Silicon: Silicon
Fullerenes and Other Polyhedral Forms ...................... 114
Vijay Kumar
3.1. Introduction ............................................. 115
3.2. Clusters of Elemental Silicon ............................ 118
3.3. Metal Encapsulation: A New Paradigm ...................... 121
3.3.1. Silicon Fullerenes ................................ 121
3.3.2. Metal Size Dependent Encapsulated Silicon
Structures ........................................ 122
3.3.3. The Electronic Factor and the Isolated
Rhombus Rule ...................................... 124
3.3.4. Reactivity as a Probe of Metal Encapsulation ...... 137
3.3.5. Vibrational Properties ............................ 137
3.3.6. Empty and Endohedral Hydrogenated Fullerene
Cages of Silicon .................................. 139
3.3.7. Absorption Spectra ................................ 142
3.3.8. Magnetic Clusters of Silicon ...................... 142
3.4. Summary .................................................. 144
Acknowledgments ............................................... 145
References .................................................... 145
4. Porous Silicon - Sensors and Future Applications ........... 149
lames L.Gole and Stephen E.Lewis
4.1. Introduction ............................................. 150
4.2. Kinds of PS .............................................. 151
4.2.1. Pore Structure in PS .............................. 151
4.2.2. PL from PS ........................................ 153
4.2.2.1. Photoluminescent Enhancement and
Stabilization ............................ 155
4.2.2.2. PL-Induced Metallization ................. 155
4.3. PS Sensors ............................................... 157
4.3.1. PS Humidity Sensors ............................... 157
4.3.2. PS Chemical Sensors ............................... 161
4.3.3. PS Gas Sensors .................................... 161
4.3.3.1. N02 Sensors .............................. 162
4.3.3.2. Hydrocarbon Sensors ...................... 164
4.3.3.3. Low-Cost Multi-application Gas Sensors ... 164
4.4. Future Technology ........................................ 168
4.4.1. Nanoparticle Photocatalytic Coating of PS ......... 168
4.4.2. Lithium Electrolyte-Based PS Microbattery
Electrodes ........................................ 170
4.5. Conclusions .............................................. 172
References .................................................... 172
5. Silicon Nanowires and Nanowire Heterostructures ............ 176
Zhaohui Zhong, Chen Yang and Charles M.Lieber
5.1. Introduction ............................................. 177
5.2. Silicon Nanowires ........................................ 177
5.2.1. Rational Synthesis and Structural
Characterization of SiNW .......................... 177
5.2.1.1. Overview of SiNW 1D Growth ............... 178
5.2.1.2. Structural Characterization of SiNWs ..... 180
5.2.1.3. Rational Control of SiNW Diameters ....... 182
5.2.2. Electronic Properties of SiNWs .................... 182
5.2.2.1. Room Temperature Electronic
Properties of SiNWs ...................... 183
5.2.2.2. Fundamental Transport Studies of SiNWs ... 186
5.2.3. SiNWs for Nanoelectronics ......................... 190
5.2.3.1. Crossed Nanowire Structures and
Devices .................................. 191
5.2.3.2. Crossed Nanowire-Based Logic Gates ....... 191
5.2.3.3. Nanowire Crossbar Arrays as Address
Decoders ................................. 193
5.2.3.4. SiNW Electronics on Non-conventional
Substrates ............................... 194
5.2.4. Large-Scale Hierarchical Organization of SiNW
Arrays ............................................ 195
5.2.4.1. Langmuir-Blodgett-Based Assembly of
Nanowires ................................ 196
5.2.4.2. Scalable Integration of Nanowire
Devices .................................. 197
5.2.4.3. High-Frequency Nanowire Circuits ......... 199
5.2.5. SiNWs as Nanoscale Sensors ........................ 200
5.2.5.1. Nanowire Field-Effect Sensors ............ 201
5.2.5.2. Single Virus Detection ................... 202
5.2.5.3. Multiplexed Detection at the Single
Virus Level .............................. 203
5.3. SiNWHeterostructures ..................................... 204
5.3.1. NiSi/SiNW Heterostructures ........................ 204
5.3.2. Modulation Doped SiNWs ............................ 204
5.3.2.1. Synthesis and Characterization
of Modulation Doped SiNWs ................ 205
5.3.2.2. Novel Applications of Modulation
Doped SiNWs .............................. 208
5.3.3. Branched and Hyper-Branched SiNWs ................. 209
5.4. Summary .................................................. 213
References .................................................... 214
6. Theoretical Advances in the Electronic and Atomic
Structures of Silicon Nanotubes and Nanowires .............. 217
Abhishek Kumar Singh, Vijay Kumar and
Yoshiyuki Kawazoe
6.1. Introduction ............................................. 218
6.2. Computational Approach ................................... 220
6.3. Silicon Nanotubes ........................................ 220
6.3.1. Metal Encapsulated Nanotubes of Silicon ........... 222
6.3.2. Electronic Structure and Bonding Nature ........... 225
6.3.3. Magnetism in Metal Encapsulated SiNTs ............. 228
6.4. Germanium Nanotubes ...................................... 231
6.4.1. Metallic and Semiconducting Nanotubes of Ge ....... 233
6.5. Silicon Nanowires ........................................ 235
6.5.1. Non-Crystalline Pristine SiNWs .................... 237
6.5.2. Crystalline Pristine SiNWs ........................ 238
6.5.3. Band Structure of SiNWs ........................... 243
6.6. Hydrogenated Nanowires ................................... 244
6.6.1. Electronic Structure of Hydrogenated SiNWs ........ 249
6.6.2. Effects of Doping and H Defects ................... 251
6.7. Nanowire Superlattices ................................... 253
6.8. Conclusion and Perspective Remarks ....................... 254
Acknowledgements .............................................. 255
References .................................................... 255
7. Phonons in Silicon Nanowires ............................... 258
Kofi W.Adu, Humberto R.Gutierrez and
Peter С.Eklund
7.1. Introduction ............................................. 259
7.2. Theoretical Models for Confined Phonons .................. 261
7.2.1. Lattice Dynamics of Si Nanowires .................. 261
7.2.2. The Richter Model for Raman Scattering from
Confined Phonons .................................. 267
7.3. Experimental Evidence of Confined Phonons in Silicon ..... 269
7.3.1. Acoustic Phonons .................................. 269
7.3.2. Optical Phonons ................................... 273
7.3.3. Thermal Conductivity .............................. 275
7.4. Effects of Inhomogeneous Laser Heating on Raman
Lineshape ................................................ 278
7.4.1. Stokes-AntiStokes Ratio as a Probe of Laser
Heating of Si Nanowires ........................... 279
7.4.2. Evolution of the Raman Band Asymmetry with
Laser Flux ........................................ 280
7.4.3. Modification of Richter's Lineshape
Function to Include Inhomogeneous Heating ......... 282
7.5. Summary and Conclusions .................................. 285
Acknowledgements .............................................. 285
References .................................................... 286
8. Quasi-One-Dimensional Silicon Nanostructures ............... 289
Yu Lin, Nevill Gonzalez Szwacki and Boris I.Yakobson
8.1. Introduction ............................................. 290
8.2. Silicon Nanowires ........................................ 290
8.2.1. Pentagonal Silicon Wires .......................... 290
8.2.1.1. WullPs Construction Generalized .......... 291
8.2.1.2. Pentagonal Shape SiNW .................... 291
8.2.1.3. Ground State of the Thinnest SiNW ........ 292
8.2.1.4. Kinetic Advantages of РII SiNW ............ 296
8.2.2. Hydrogen-Passivated Silicon Wires ................. 297
8.3. Metal Silicide ........................................... 300
8.3.1. Endohedral Silicon Nanotubes ...................... 301
8.3.2. Yttrium Silicide NW ............................... 307
8.3.3. Energy Decomposition .............................. 308
Acknowledgements .............................................. 311
References .................................................... 312
9. Low-dimensional Silicon as a Photonic Material ............. 314
N.Daldosso and L.Pavesi
9.1. The Need of a Silicon-Based Photonics .................... 314
9.2. Various Approaches to a Silicon Light Source ............. 316
9.2.1. Silicon Raman Laser ............................... 317
9.2.2. Bulk Silicon Light Emitting Diodes ................ 319
9.3. Optical Gain in Silicon Nanocrystals ..................... 321
9.3.1. CW and TR Measurements ............................ 322
9.3.2. Gain Model: Four-Level System ..................... 325
9.3.3. Other Key Ingredients ............................ 327
9.4. Er Coupled Si Nanocrystal Optical Amplifiers ............. 328
9.4.1. Er3+ Internal Transition .......................... 329
9.4.2. Er3+ and Si-nc Interactions ....................... 330
9.4.3. Er3+ Cross Sections ............................... 330
9.5. Conclusions .............................................. 332
Acknowledgements .............................................. 333
References .................................................... 333
10.Nanosilicon Single-Electron Transistors and Memory ......... 335
Z.A.K.Durrani and H.Ahmed
10.1.Introduction ............................................. 335
10.1.1. Single-Electron and Quantum Confinement
Effects .......................................... 337
10.2.Nanosilicon SETs ......................................... 341
10.2.1. Conduction in Continuous Nanocrystalline
Silicon Films .................................... 341
10.2.2. Silicon Nanowire SETs ............................ 343
10.2.3. Point-Contact SETs: Room Temperature Operation ... 346
10.2.4. "Grain-Boundary" Engineering ..................... 350
10.2.5. Single-Electron Transistors Using Silicon
Nanocrystals ..................................... 351
10.2.6. Comparison with Crystalline Silicon SETs ......... 352
10.3.Electron Coupling Effects in Nanosilicon ................. 352
10.3.1. Electrostatic Coupling Effects ................... 354
10.3.2. Electron Wavefunction Coupling Effects ........... 354
10.4.Nanosilicon Memory ....................................... 356
References .................................................... 358
Index ......................................................... 361
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